Cone beam computed tomography (CBCT) is an X-ray imaging modality capable of acquiring three-dimensional information of the human anatomy with a substantially lower radiation dose to the patient as compared to conventional medical computed tomography (CT) systems. Cone beam CT systems capture volumetric data sets by using a high frame rate digital radiography (DR) detector and an x-ray source, typically affixed to a gantry that rotates about the subject to be imaged, directing, from various points along its orbit around the subject, a divergent cone beam of x-rays toward the subject. The CBCT system captures projections throughout the rotation, for example, one 2-D projection image at every degree of rotation. The projections are then reconstructed into a 3D volume image using various techniques. Among the most common methods for reconstructing the 3-D volume image are filtered back projection approaches. One area of particular interest for CBCT use is in endodontics. In conventional practice, detection of a problem responsive to endodontic treatment begins with the patient's report of pain. The practitioner works with the patient to isolate the suspect tooth and may obtain one or more two-dimensional (2-D) periapical radiographs to help identify any abnormalities of the root structure and surrounding bone structure. In many cases, visual inspection of the 2-D image can help to identify the problem. However, detection of some types of conditions remains a challenge with conventional 2-D images. In particular, some types of Vertical root fracture (VRF) can be difficult to detect in the periapical image. Vertical root fracture is a severe type of tooth fracture that affects the root, causing pain due to infection and inflammation and often leading to tooth extraction.
The improved image quality available from CBCT imaging and its capability for displaying very low contrast tissue regions makes CBCT a promising technology for assessment of VRF and other endodontic conditions. This includes use of CBCT imaging to support root canal therapy, as shown in the sequence of FIG. 1. In this type of treatment, an infected tooth 20 has an abscess 22 that is to be treated. An opening 24 is made in tooth 20 and a tool 28 used to access and remove infected material. A plugger 30 then fills root portions of tooth 20 with gutta percha or other suitable material. The tooth 20 can then be repaired with a filling 34 or with a crown 36 that is fitted onto a post 38 inserted by the practitioner.
While CBCT imaging can be used to improve detection of VRF and other conditions requiring endodontic treatment, however, difficulties remain. Manipulating the CBCT image can be challenging, particularly for practitioners and technicians who are new to volume imaging technology. Isolating the particular views that most distinctly reveal the problem condition can be difficult or frustrating for the practitioner, burdening the user with a time commitment for training and using the CBCT system.
Thus, it can be seen that there is a need for an interactive operator interface that provides tools that can be quickly learned and that provides a more intuitive viewer experience, allowing the practitioner to make effective use of CBCT imaging for endodontic applications.